M-phase or M-ary PSK signalling is a modulation technique commonly employed in both continuous and burst communication systems. At the receiver, data, that has been originally quantized into one of M levels and transmitted at some i.sup.th phase angle .theta., where 0.ltoreq..theta..ltoreq.M, relative to a reference angle .theta..sub.REF, is recovered through the use of a reference phase generator by comparing successively received symbols with the reference. Typically, the generation of the phase reference is accomplished through the use of a closed (phase-lock) loop. In a closed loop system it is necessary to have a continuously available signal in order for the receiver to "lock-on" to the reference with which unknown data symbol-representative phase vectors are to be compared. As a result, where the data transmission is in a burst format the closed loop system is subjected to a substantial loss of data as it must reaquire the reference for each burst. Moreover, in any locking loop scheme there is a certain amount of data loss during the acquisition (locking) interval.